The objectives of the proposed research are to increase understanding of host factors which interact with microbes and microbial factors to provide resistance to infectious disease. The long term goals are to identify with precision, cellular and humoral components of the inflammatory response which bring about localization, killing and digestion of invading bacteria and fungi. The patient categories that will be studied includes neonates, patients with malignancy, patients with compromised immune status and patients with known susceptibility to recurrent bacterial and fungal disease. The cellular functions that will be studied include phagocytosis, intracellular killing, leukotaxis, migration, adhesiveness and reduction of nitroblue tetrazolium. The humoral factors analyzed will be opsonic activity and activity of activated complement components. The interaction of host factors with Candida will be studied in patients with fungal disease and in experimental animals. Counter-immunoelectrophoresis will be used to determine antibody response to Candida antigens. This method will provide rapid clinical information in patients with suspected systemic Candida infection. To determine virulence factors of Candida albicans the supernatant cell wall and cytoplasmic extracts of Candida cultures will be separated and assayed for immunogenicity, chemotactic activity, and enhancement or inhibition of phagocytosis.